Tahm Kench, the River King

{b}{g},{t}: Exile target creature with power
less than or equal to Tahm Kench's power.
{b/g}{b/g}{b/g}: Put target creature exiled by Tahm Kench into it's owner's graveyard.
Put a number of +1/+1 counters on Tahm Kench equal to that creature's power.